PA28 will not start till OAT 6 deg C
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Join Date: Apr 2000
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PA28 will not start till OAT 6 deg C
Can anyone share a light on this one. Over the last few weeks had trouble starting PA28's till mid morning when the temp got up. I was given a story about the Carb bowl being iced up so it got no fuel into the induction manifold even through priming??? <img src="confused.gif" border="0">
Join Date: Jun 2001
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Not unusual at all for carborated engines, this is a good time to switch to fuel injected :-)
The problem with starting the engine comes from
a cold carborater coupled with a weaker battery from the cold temps. The best advice to give in regards to cold starts is to preheat the engine for a while. While on the subject, remember to have someone manually turn the prop a few times to limber up the oil, in the cold temps the oil becomes quite dense and increases the stress on the battery
The problem with starting the engine comes from
a cold carborater coupled with a weaker battery from the cold temps. The best advice to give in regards to cold starts is to preheat the engine for a while. While on the subject, remember to have someone manually turn the prop a few times to limber up the oil, in the cold temps the oil becomes quite dense and increases the stress on the battery
If the engine cranks over normally (after a few rotations of the prop by hand - keys out, of course), the problem is unlikely to be battery related. Weak impulse magneto, inefficient primer, the engine cranking slowly due to cold, thick oil so that the impulse mag fires at the wrong moment, poor fuel vapourisation...how I wish we had aeroplane engines as reliable as my Honda VTEC!!
For some odd reason our 161 Warriors are often pigs to start compared to the 140C Cherokees; considerable priming and coaxing being needed to get the little $ods going in cold weather. Whereas I never had any difficulty with the injector-carburettor fitted to the IO-360 in the Bulldog, hot or cold.
For some odd reason our 161 Warriors are often pigs to start compared to the 140C Cherokees; considerable priming and coaxing being needed to get the little $ods going in cold weather. Whereas I never had any difficulty with the injector-carburettor fitted to the IO-360 in the Bulldog, hot or cold.
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Beagle
I always found priming about 4 times and just 'cracking the throttle open', always worked for me on RG. If you opened the throttle to the recommended 1/4in it almost always failed to start when very cold. How is RG?, my friend in PLH tells me that it was 'AN124ed' recently.
I always found priming about 4 times and just 'cracking the throttle open', always worked for me on RG. If you opened the throttle to the recommended 1/4in it almost always failed to start when very cold. How is RG?, my friend in PLH tells me that it was 'AN124ed' recently.
Yes - I agree that RG needed rather more priming and a larger throttle setting than most.
Regrettably she is still looking the worst for being blown over by an Il76 whose crew were using excess thrust to manoeuvre. That was nearly 3 months ago - the matter is now being dealt with by lawyers, so further comment is inappropriate at this stage.
Regrettably she is still looking the worst for being blown over by an Il76 whose crew were using excess thrust to manoeuvre. That was nearly 3 months ago - the matter is now being dealt with by lawyers, so further comment is inappropriate at this stage.
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if the carb is iced up you will still get fuel to the engine by priming, the engine would start with the primed fuel and then stop again. When it is really cold the fuel does not vaporise as much, you may need more priming. Sometimes one or more of the priming nozzles blocks up and you do not notice this until the really cold days, a lot of lycomings are not fitted with the nozzles to all the cylinders and this can make it worse if one blocks, it is a simple job to take them off and clean them, you might want to try it. Mind you nice heated hangar always helps!!!! I don't agree with this turning the engine over to warm the oil business, don't think it will get any heat in the oil and as you have got sticky oil and no oil pressure you might be doing damage to the engine, a guy the shell aero oils told me that you should never do it!!! But then others swear by it!!!!
[ 29 December 2001: Message edited by: grounded1 ]</p>
[ 29 December 2001: Message edited by: grounded1 ]</p>
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As an operator of 4 PA28's you will find that the only solution is to change the left mag which is probably giving a week spark at low temperatures.
I have had to change the left mag on a different a/c on each of the last two winters,and am waiting
for the spares suppliers to open again after the new year to order another left mag for another of the Cherokee's.
However, before going to this expensive option do get the primer system injectors checked for blockages,I have all our injectors cleaned every year but admittedly the a/c are achieving a lot of hours each year.
regards
I have had to change the left mag on a different a/c on each of the last two winters,and am waiting
for the spares suppliers to open again after the new year to order another left mag for another of the Cherokee's.
However, before going to this expensive option do get the primer system injectors checked for blockages,I have all our injectors cleaned every year but admittedly the a/c are achieving a lot of hours each year.
regards
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Just a quick thought, has anyone checked the Impulse coupling coz in the past 2 Months I've changed three of the little sods.
Something else I've found useful as well especially on 152’s is to prime the Engine, Set the throttle and mixture, leave the primer out and when/if it fires slooooowly advance the primer but don’t forget to lock it coz its embarrassing
[ 08 January 2002: Message edited by: 100LL ]</p>
Something else I've found useful as well especially on 152’s is to prime the Engine, Set the throttle and mixture, leave the primer out and when/if it fires slooooowly advance the primer but don’t forget to lock it coz its embarrassing
[ 08 January 2002: Message edited by: 100LL ]</p>
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A useful remedy (unless there is a mechanical problem with the left magneto of course) is to deliberately over-prime and use the flooded start technique.
I have done this in OAT down to 0°C or so in Lycomings with three out of four cylinders connected to the primer. Works with a weak battery too - engine should start on first or second revolution.
Secondly, try waiting up to a full minute after priming before turning the engine. I think (not certain) that this helps because it gives cold fuel time to vaporise in the cylinder, helping combustion with a weak spark.
cheers,
O8
[ 09 January 2002: Message edited by: Oktas8 ]</p>
I have done this in OAT down to 0°C or so in Lycomings with three out of four cylinders connected to the primer. Works with a weak battery too - engine should start on first or second revolution.
Secondly, try waiting up to a full minute after priming before turning the engine. I think (not certain) that this helps because it gives cold fuel time to vaporise in the cylinder, helping combustion with a weak spark.
cheers,
O8
[ 09 January 2002: Message edited by: Oktas8 ]</p>
